The Surgery Branch is vigorously involved in the assessment of the efficacy of total parenteral nutrition as a means of nutritional support of the cancer bearing host. These studies are directed at utilizing new methodologies employing stable isotopes and labelled substrates combined with standard assessment of nitrogen balance and 3-methylhistidine excretion as determinants of host-protein preservation. In addition, two prospective randomized studies have been initiated as mentioned under 03801-09. Within the lab, attempts to nutritionally deprive human tissue culture cell lines of essential amino acids are continuing. The interest in animal models of protein depletion and methods for preservation of host tissue by animal TPN, exercise an steroids continues. Continued effort is being made in the elucidation of function in fresh and cryopreserved parathyroid and other endocrine tissues.